Jerking at 2300 RPM's

Next time this happens, look at road speed, and not engine speed. If this happens at around thirty five to forty mph, and only after the engine is warmed up, and not at higher road speeds, it is likely a shudder from the transmission's torque converter. That is the result of using the wrong transmission fluid.

The clue to identifying this is when the problem is occurring, hold the accelerator pedal perfectly steady, then briefly tap the brake pedal with your left foot. If the torque converter shudder is the cause, it will clear up for about two or three seconds, then resume, each time you tap the brake pedal.

Did you do the brake pedal tap test?

Heading out of town tomorrow for the weekend at an old car show swap meet. Do not panic if I do not reply right away. I will be back Monday night to see how you are doing.